1. Perspective Projection 透視投影
2. 計算3D point的2D Coordinates的數學知識
從這個翻譯上來看的話，是如何把3D空間中的一個點放到2D map裏，然後得到在2D map裏對應的座標。
2.1 從頭到尾解釋找到3D point的2D pixel座標
之前的章節已經討論了perspective projection process which is used to convert the position of that point in 3D space to a position on the surface of the image.(3D 空間裏的點投到image表面的position就是依據的perspective Projection). but this position is not expressed in terms of pixels coordinates 意思是：是在2D image surface上有點了，但是不是具體的座標形式
So how do we actually find the final 2D pixel coordinates of the projected point in the image?